Evolution of the ermine moth pheromone tetradecyl acetate

The nine sympatric forms of small ermine moths of the genus Yponomeuta (Lepidoptere; Yponomeutidae) in the west palaearctic region show various degrees of differentiation^1,2, including among other characteristics, differences in their sexual pheromones³. As is the case for many other moths⁴, the ermine moths so far analysed use delta 11-unsaturated acetates ((Z)-11-tetradecenyl, (E)-11-tetradecenyl and (Z)-11-hexadecenyl acetate) as primary pheromone components. Here for the first time in Lepidoptera we report that a saturated acetate, tetradecyl acetate, is the primary pheromone component⁵ of Y. rorellus (Hübner). Y. rorellus is almost monomorphic with respect to isoenzyme variation⁶ and has fewer chromosomes than its relatives^7,8. We suggest that it has evolved through loss of unsaturated pheromone components in a 'genetic revolution' at a population bottleneck, and by the founders of the new species filling an empty communication niche, separated from that of the ancestral species.